Contagious Diseases of Insects. 309 



latter averaging 1 ^ in diameter, with an occasional Bacillus 

 like those already several times mentioned. Micrococci and 

 bacilli were, however, less abundant in these fluids than is com- 

 monly the case with larvae destroyed by bacterial disease. 



In a peculiar larva which died July 2, a small specimen 

 that had scarcely grown since it was first placed in the cage, a 

 few micrococci were found, and a considerable quantity of the 

 mulberry granules, although this individual caterpillar must 

 have been far from the pupal stage of development. 



In another larva examined at the same time, likewise 

 dwarfed, although larger than the preceding, the blood was 

 gray with the usual Micrococcus, both free and in masses, and 

 contained likewise great numbers of mulberry cells and gran- 

 ules. On the 12th July a larva died in whose blood no bac- 

 teria were detected, save a few of the usual bacilli. Its fluids 

 contained, however, an immense number of mulberry cells and 

 granules. 



Prom the 12th to the 14th July eight more larvae died in 

 this lot with symptoms and microscopic characters like those 

 already described. the body usually somewhat shrunken and 

 flaccid and the colors unchanged. The blood was occasionally 

 gray with micrococci, but more commonly differed in appear- 

 ance from that of healthy larvae, only by the slightly yellowish 

 or whitish tinge. The original Bacillus found in the earlier 

 specimens occurred but once in these, and then in trifling quan- 

 tity. The ordinary Micrococcus was more commonly present, 

 sometimes, indeed, profusely abundant, but at other times in 

 relatively trivial numbers. The unvarying and characteristic 

 feature was the number of free cells in the blood, of variable 

 form and size, some of them being altered blood corpuscles and 

 others evidently derived from the fatty bodies. These occurred 

 in all stages of segmentation, from a mere trace of commenc- 

 ing subdivision to a complete separation of the entire contents 

 of the cell into more or less equal granules. The absence of an 

 enclosing wall was unquestionably evident, granular masses 

 being occasionally found from which a single one of the mul- 

 berry granules had broken away, leaving the remainder undis- 

 turbed. When the segmentation of these cells was incomplete 

 or indefinite, they readily reverted to nucleated cells with gran- 



